The present invention relates to force measuring transducers for measuring the force between a magnetic data head and a disc surface in a disc drive data storage system. More particularly, the present invention relates to a micro-force transducer fabricated integrally with a slider body using head processing techniques.
Disc drive data storage systems utilize read/write heads having a slider body which "flies" above a rotating magnetic storage disc. The term "head" typically refers to a combination of the slider and magnetic transducers carried by, or embedded within, the slider. A fundamental problem in head/disc tribology is the lack of understanding of the forces which occur during contact between the head and the disc During the early phases of contact start-stop (CSS), the force between the head and the disc is fundamentally one of solid-to-solid contact. Asperities on the disc surface interact with asperities on the slider's air bearing surface (ABS) and the entire preload force from the head suspension system is supported through these solid-to-solid contacts between the head and the disc. As the disc comes up to full rotational speed, for a high-flying head design, the preload force from the suspension is supported between the head and the disc through a thin layer of air beneath the ABS of the slider body. The air movement, which is caused by the rotating disc, maintains the head slider flying above the disc.
In proximity contact recording, portions of the head slider are allowed to be in occasional or intermittent contact with the disc surface during a break-in period. As the disc rotates, the intermittent solid-to-solid contact between the head slider and the disc wears down asperities on the head slider and on the disc surface. After the break-in period during which asperities are reduced in size or eliminated, the head slider is controlled in a normal head/disc interface manner with the slider body flying above the disc with minimal contact between the two.
In proximity contact recording, for a new head/disc interface, when the disc is at full speed most of the suspension preload force is supported between the head and the disc through the air bearing film. A small fraction of the suspension preload is supported by solid-to-solid contact between the head and the disc. The lack of understanding of the magnitudes of the solid-to-solid contact forces between the head and the disc during the break-in period is a fundamental problem in proximity contact recording. Frequently, the solid-to-solid contact forces between the head and the disc during proximity contact recording are estimated using simulation programs. In the alternative, piezo-electric materials have been bonded to the top surface of a slider body (opposite the ABS) in an attempt to obtain more information about the forces involved. When the slider body contacts the surface of the disc, a voltage is generated by the piezo-electric material. This gathered information is intended to be used in ABS and disc design. However, in the prior art, there has been no way to correlate the magnitude of the voltage generated to the actual force between the head slider and the disc. Consequently, there is a need for a head/disc force transducer which can provide information on the magnitude of contact forces between the head slider and the disc surface.